Sphenoethmoidal mucocele masquerading as trochlear palsy.

Acquired vertical strabismus is commonly caused by superior oblique muscle palsy, often resulting from blunt head trauma or vascular problems, and less often from brain tumors, meningitis, and aneurysms. To date, mucoceles in the ethmoid sinus have rarely been reported as a cause for superior oblique muscle palsy. We report a case of trochlear nerve palsy and subsequent optic neuropathy caused by a mucocele in the ethmoid and sphenoid sinuses.